The present invention relates to an authentication method of an ad hoc network and a wireless communication terminal thereof, and more particularly to an ad hoc network authentication method that is suitable for an ad hoc network in which connection relationships are fluid and that reduces the processing load of wireless communication terminals by efficiently performing processing for mutual authentication between wireless communication terminals, and a wireless communication terminal thereof.
An ad hoc network is a network in which wireless communication terminals (personal computers, PDAs, mobile telephones and the like) do not require access points that intervene in communication between the terminals and in which the terminals can connect autonomously with each other. Therefore an ad hoc network does not require a base station or access points and makes it possible to configure a network at a low cost in a location without such infrastructure, and is thus effective as means for configuring a simple network in a limited area.
Thus, without depending on existing specific network infrastructure such as a telephone line, a mobile phone network or an internetwork, an ad hoc network enables the participating communication terminals to behave in an autonomous and decentralized manner on an equal basis with each other and allows communication terminal devices (nodes) within the transmission range to exchange information with each other directly by wireless communication. It is also possible for nodes that the radio waves do not reach and which consequently cannot exchange information directly with other nodes to exchange information through a node that is partway along the communication route relaying the information (multihop wireless communication).
In this kind of ad hoc network, when configuring a closed communication network that enables communication only among communication terminal devices belonging to a particular group, in order to ensure the security of information within the group it is necessary to prevent connections by communication terminal devices that do not belong to the group and also prevent leakage of communication data. It is also necessary to perform communication securely and smoothly even when nodes move and the connection relationships between nodes change.
Regarding security in a closed communication network, for example JP-A-2002-111679 discloses technology for ensuring security in a group communication system configuring a closed communication network autonomously with many and unspecified communication terminals by distributing a common key for encryption or the like. More specifically, JP-A-2002-111679 proposes a method in which a communication terminal device that is the source of a calling message establishes a p-to-p (peer-to-peer) connection with a communication terminal device that responds to the message, and in which a common key can be shared within a group by distributing the common key with a public key of the communication terminal device on the responding side.
Further, EP-1102430A1 discloses technology whereby, when an arbitrary communication terminal device wants to join an ad hoc network, the terminal is authenticated by a node with which it is not directly connected.
Furthermore, JP-A-2002-300152 discloses an authentication method used in a case where a plurality of base stations and mobile communication terminals are present and a connection changed to another base station from a base station that had a connection with a particular mobile communication terminal device. More specifically, an authentication consecutive key is generated at a particular base station using a key that is shared by base stations and distributed to the communication terminal device. When the communication terminal device connects with another base station, the communication terminal device performs authentication with the other base station using the authentication consecutive key that it received.